5G in smart cities

Digital technologies for smart cities will, among many other aspects, facilitate the changes needed to increase sustainability and foster the adaptation to climate change. The evolution of mobile networks - in the short term with 5G - brings as main novelty the provision of differentiated services for communication between equipment (devices and services) and people. This is reflected in a greater capacity to interconnect huge amounts of devices per square meter (the massive Machine Type Communications - mMTC service), the possibility of having high reliability and very low latency in some communications (the Ultra Reliable Low Latency Communications - URLLC service), and the ability to provide high throughput for specific applications (the enhanced Mobile Broadband - eMBB service). These services will be provided not only through the installation of new infrastructures for the various frequency bands of the access networks (700MHz, 3.5GHz, 26GHz), but also via the integration and evolution of existing technologies (including 3G/4G and NB- IoT, WiFi, etc.). Although the use of new frequencies has raised concern about the risks to people and animals' health, there is no scientific evidence to support it so far, as detailed in a recent study by the EC Joint Research Center.⁽¹⁾

There will also be fundamental changes in the organisation of services that build the core of the network. Core services will become virtualised, leveraging Network Function Virtualization (NFV) technology. They will no longer be strongly integrated with the equipment where they are executed, thus enabling an organisation of the core functionalities as micro-services running on generic equipment. .

Existirão ainda alterações fundamentais na organização dos serviços que constituem o núcleo da rede, que passam a ser aplicações virtualizadas, denominadaos Network Function Virtualization (NFV). Os serviços deixam também de estar fortemente integrados com os equipamentos onde executam, permitindo uma organização em micro-serviços sobre equipamentos genéricos.

From an economic point of view, the possibility of using generic equipment and software modules from different suppliers is expected to create many opportunities for innovation in network components. A great effort is being invested towards the development of open-source software components, mainly under O-RAN,⁽²⁾ with many operators involved. This will push innovation in network components.

What does this mean for smart cities?

The greater sensing capacity will facilitate the collection of data with finer spatiotemporal granularity, allowing for greater knowledge about all the city's processes, both public and private. This includes the monitoring of infrastructures, natural resources, microclimates, rainwater, as well as following-up the implementation of public policies, etc. This data will also feed a digital twin of the city, which can be used to study the impact of public policies, events, or to predict anomalous occurrences and their consequences. This more accurate and granular information allied to greater actuation capacity, will also favour a more agile automated control of some of these processes, using the processing capacity of cloud computing. Examples of these scenarios range from managing mobility and air quality, the electric grid, local producer-consumer networks or the electric car charging network, to personalised warnings about health risks in cases of extreme weather events, since it will become possible to assess risk at both the individual and neighbourhood level. Greater knowledge about the city will also enable the adequate management of the network infrastructure itself, assessing where and when certain services will be needed. The time scales of these control applications range from several minutes to hours.

The high reliability and low latency URLLC service will allow other types of applications, for fine control of various processes in sub-second timescales. The easiest application to imagine is managing traffic scenarios with autonomous cars and all other users of public spaces, vulnerable road users. In these scenarios, the various mobile nodes (vehicles, pedestrians, cyclists, other new means of transportation) must communicate with each other within milliseconds, in order to exchange information collected by their multiple sensors, allowing a better understanding of each one’s situation. In busy areas, where traffic situations are more complex, data processing is expected to not take place exclusively on the mobile nodes themselves, but rather be supported by more powerful computing resources available close to the network access (as opposed to the cloud, on the network's core). The usage of these computational resources with low latency can only be achieved by a very efficient and granular network management, enabled by slicing, SDN and NFV technologies.

Another relevant scenario is the use of augmented reality for various daily tasks, which will be supported by eMBB, eventually combined with others. The city's data flows and the possibility of precise location, combined with high-resolution multimedia content, allow highly innovative mixed reality experiences. An example is the maintenance of infrastructures and equipment supported by remote experts. Others are entertainment applications associated with leisure and tourism in public spaces, e.g., a game with virtual beings in the city space, a guided tour in a Star Wars environment accompanied by Jedi and Sik, or the participation in the liberal wars in Porto.

We dare to say that one of the biggest challenges to the technical realisation of these scenarios is the security of all components and of the integrated system. The opening up of communication networks, the greater number of entry points into the network, and the use of open and interoperable components, increase the attack surface and make it more complex. The scientific and technology community are currently addressing these challenges, and we are confident that they will timely find adequate solutions.

5G is an integrative term for a broad set of innovative technologies that are expected to promote a high degree of openness and innovation, both in the network itself and in the applications that run on top of it. 6G is now starting to grow as a research area, focusing on the evolution towards increasingly integrated architectures for communications and computing networks, taking advantage of artificial intelligence to achieve greater efficiency, with a focus on scalability and energy. Communications and networks will continue to evolve to interconnect a dense and ubiquitous fabric of computing nodes that will support services increasingly focused on improving citizens' quality of life.